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Lanthanide-Based $T_{2ex}$ and CEST Complexes Provide Insights into the Design of pH Sensitive MRI Agents
| Content Provider | Scilit |
|---|---|
| Author | Zhang, Lei Martins, André F. Zhao, Piyu Wu, Yunkou Tircsó, Gyula Sherry, A. Dean |
| Copyright Year | 2017 |
| Description | Journal: Angewandte Chemie International Edition The CEST and $T_{1}/T_{2}$ relaxation properties of a series of $Eu^{3+}$ and $Dy^{3+}$ DOTA‐tetraamide complexes with four appended primary amine groups are measured as a function of pH. The CEST signals in the $Eu^{3+}$ complexes show a strong CEST signal after the pH was reduced from 8 to 5. The opposite trend was observed for the $Dy^{3+}$ complexes where the $r_{2ex}$ of bulk water protons increased dramatically from ca. 1.5 $mm^{−1}$ $s^{−1}$ to 13 $mm^{−1}$ $s^{−1}$ between pH 5 and 9 while $r_{1}$ remained unchanged. A fit of the CEST data $(Eu^{3+}$ complexes) to Bloch theory and the $T_{2ex}$ data $(Dy^{3+}$ complexes) to Swift–Connick theory provided the proton‐exchange rates as a function of pH. These data showed that the four amine groups contribute significantly to proton‐catalyzed exchange of the $Ln^{3+}$‐bound water protons even though their $pK_{a}$’s are much higher than the observed CEST or $T_{2ex}$ effects. This demonstrated the utility of using appended acidic/basic groups to catalyze prototropic exchange for imaging tissue pH by MRI. |
| Related Links | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5879776/pdf |
| Ending Page | 16630 |
| Page Count | 5 |
| Starting Page | 16626 |
| ISSN | 14337851 |
| e-ISSN | 15213773 |
| DOI | 10.1002/anie.201707959 |
| Journal | Angewandte Chemie International Edition |
| Issue Number | 52 |
| Volume Number | 56 |
| Language | English |
| Publisher | Wiley-Blackwell |
| Publisher Date | 2017-10-11 |
| Access Restriction | Open |
| Subject Keyword | Journal: Angewandte Chemie International Edition Inorganic Chemistry Amide Ligands Chemical Exchange Saturation Transfer (cest) Ph Responsive Lanthanide Complexes Mri Contrast Agents |
| Content Type | Text |
| Resource Type | Article |
| Subject | Chemistry Catalysis |
